What a HUGE relief to find the EXACT size filter needed for an old school type furnace. AND even better, I was able to get the highest MERV rating my furnace can use to help clean the air in my home. During cold, flu & Covid season an extra little bit of peace of mind.
I use the merv 11 filters in locomotive cab HVAC systems. They are double stacked and work great filtering out not only dust particles but whatever exhaust particulate enters the cab.